1. Field of the Invention
The invention is related to a technique for improving the extinction ratio of a light modulator which modulates light passing through by an electro-optic crystal substrate.
2. Description of the Related Art
The index of refraction of an electro-optical crystal substrate formed using lithium niobate (LiNbO3), lithium tantalite (LiTaO3), etc. changes in accordance with a voltage which is applied from outside. Noting this, JP-A-2010-152214 proposes a light modulator which has a structure that a distribution of the index of refraction is generated inside an electro-optical crystal substrate in accordance with a voltage applied from outside and the distribution of the index of refraction functions as a diffraction grating so that light is modulated. In short, using the diffraction grating which is created inside the electro-optical crystal substrate in accordance with the applied voltage, the light modulator modulates light which is passing through the electro-optical crystal substrate.